Hey there Timbarin, basically all this is from overwatering. You can see the overwatering based on the wrinkled aspect of the leaves and the puffy space between the veins of the leaves. What happens is the humidity will activate "dormant" white fly eggs and they will wake up hatch and fly away, but first they will eat a bit of leaf. I think that's what happened here. Basically if you stop overwatering the eggs will naturally die and this problem should stop spreading. To never overwater again, try the lifting pot method
www.youtube.com/watch Hope this helps ! π